Do Hair Dye and Perms Cause Hair Loss? Breakage, Scalp Allergy and When to See a Doctor

Do hair dye and perms cause hair loss? Most of the time the chemicals damage the hair itself, leaving it brittle and prone to snapping, while the follicles stay intact. Only when a dye allergy or chemical burn clearly inflames the scalp can the follicles be affected, leading to a period of noticeable shedding.

Patients often come in holding a handful of hair and ask me, “Doctor, I had my hair bleached last month and now it keeps falling out when I brush it. Have the chemicals ruined my follicles?” I first ask them to lay the fallen hairs on a sheet of white paper and look: are they short broken pieces, or whole hairs with the root attached? That one step often settles most of the question.

Key points: the usual effect of colouring and perming is damage to the hair shaft and breakage, while the follicles are usually intact. Once you cut back on chemical treatments and trim the damaged lengths, new growth is mostly unaffected. A red, swollen, itchy or stinging scalp, blisters or weeping after colouring may be contact dermatitis: stop the product and see a doctor. If you are losing whole hairs with the root for more than three months, or your parting is widening or your hairline receding, telogen effluvium or pattern hair loss is more likely and needs an in-person medical assessment.

Can colouring or perming damage the hair follicles?

When colouring and perming are done correctly, the chemicals act mainly on the hair shaft above the scalp. The shaft is keratinised and not alive; the follicle sits beneath the scalp and is what produces new hair.

Bleaching, colouring, perming and straightening all involve opening the cuticle or changing the chemical bonds inside the hair. Dermatology literature notes that the cuticle and the cementing structures inside the shaft are especially vulnerable to these treatments; damaged hair becomes dry, frizzy and split, and snaps easily when brushed or blow-dried.

So when people feel their hair “keeps falling out after colouring”, what they are losing is mostly broken strands, not dead follicles. The exceptions are when the chemicals trigger scalp allergy or inflammation, or are left on long enough to cause a chemical burn. Then the problem moves from the hair to the scalp, which I cover below.

How do you tell broken hair from hair that has fallen out?

A simple method is to collect the fallen hairs and look at both ends on white paper or a dark towel. A hair that has shed naturally usually has a small white bulb at the scalp end, which is the resting-phase root. A broken hair has a snapped end on both sides, and the pieces vary in length.

Then look at where the hair is going from. Breakage mostly affects the dry, treated ends or mid-lengths, so the top looks frizzy and uneven. True hair loss may widen the parting, push the hairline back or thin the hair overall.

If you have both, or cannot tell, put the fallen hairs in a zip bag and bring them to your appointment. A doctor looking at the roots and scalp with a dermatoscope will be far more accurate than guessing.

Bleaching, colouring, perming, straightening: which is hardest on hair?

The damage depends on the strength of the product, how often it is used and how long it is left on, so there is no fixed ranking. In general, bleaching to lift the colour, and perming or straightening to change the hair’s structure, put the most strain on the shaft.

The American Academy of Dermatology recommends staying within three shades of your natural colour; going darker is usually less damaging than going lighter. Lifting a lot needs stronger peroxide, and the damage is more obvious.

Perming and straightening first break the chemical bonds in the hair and then set them again, usually with alkaline products. If a product is left on too long, is too strong, or the scalp already has a wound, it can sting or even burn. A burn severe enough to scar may stop that small patch of follicles from growing hair again, so if your scalp stings or feels hot during a treatment, say so straight away.

Is an itchy, red, swollen scalp after colouring an allergy?

It may be. Dermatitis after dye touches the scalp falls broadly into two types. Irritant dermatitis is caused by the product itself and often stings or reddens during or right after the treatment. Allergic contact dermatitis may appear from a few hours to two or three days later, and the next exposure is often worse.

PPD (para-phenylenediamine) and related dyes in oxidative hair colour are common allergens. A 2024 review of allergic contact dermatitis of the scalp notes that PPD is a frequently identified cause of scalp allergy across studies, and that scalp allergy can look atypical: besides redness, itch and flaking, it may show up as thinning or hair loss.

In severe reactions, the scalp, forehead, the skin behind the ears and even the eyelids can swell, with blisters and weeping. A strongly inflamed scalp may be followed by a period of obvious shedding. In most cases the hair has a chance to regrow once the inflammation is controlled, but a doctor should still examine it.

The redness, itch and flaking of a scalp allergy can look like seborrhoeic dermatitis. If you are also worried that a repeatedly red, itchy, flaky scalp could affect a future transplant, see Can You Have a Hair Transplant With Seborrhoeic Dermatitis? Scalp Stability and Timing.

Is a patch test before colouring useful?

In Taiwan, where our clinic is based, the labelling requirements for hair dyes published by the Ministry of Health and Welfare state that hair dye may cause allergic reactions and advise consulting a dermatologist or doing a skin allergy test before use. If you colour at home, follow the instructions and test behind the ear or on the inner arm first, then wait the full time the instructions specify before judging the result.

However, the British Society for Cutaneous Allergy’s patient information also points out that self-testing before colouring can help pick up problems but is not completely reliable. If you have had a red, swollen or blistering scalp after colouring before, or a skin reaction after a black henna tattoo, do not rely on a self-test alone; see a dermatologist first and arrange formal patch testing if needed.

Stop if you notice any of these

• Severe stinging or burning during a treatment: rinse the product off immediately; do not wait for the timer
• Redness or swelling of the scalp, face, behind the ears or eyelids, with a rash, blisters or weeping
• A scalp so itchy you scratch it raw or it crusts, or symptoms getting worse over several days
• Difficulty breathing, a tight throat or a rash all over the body: seek medical care immediately

If any of these happen, stop all colouring and perming and see a doctor as soon as you can. Once a dye allergy is confirmed, discuss with your doctor which products to use in future; do not simply try a different brand.

If hair loss increases after colouring or perming, is the treatment always to blame?

Not necessarily. Colouring or perming and hair loss often just happen to line up in time. So in clinic I ask a few more questions: roughly when the shedding started, whether it is broken hair or whole hairs, and whether in recent months you have been ill, had surgery, given birth, lost weight quickly or been under unusual stress.

Telogen effluvium usually appears a few months after an event such as illness, fever or stress. Many people happen to have their hair done in that window and blame the chemicals. If you are also worried that your hair loss has suddenly sped up, see Sudden Faster Hair Loss: 5 Common Causes and How Doctors Assess It.

Pattern hair loss develops gradually and is linked to genetics and androgens, not to colouring or perming. But when hair has already become finer, breakage from chemical treatments makes the thinning look more obvious. If you are also wondering whether you have pattern hair loss, see What Is Male Pattern Hair Loss? Causes, Stages and Treatment.

In women, the more common pattern is a gradually widening parting and a thinning crown, while the hairline stays largely in place. This pattern is not caused by colouring or perming either, and a doctor can assess how far the follicles have miniaturised.

Tight ponytails, braids or extensions worn for long periods, or perm rods wound too tightly, repeatedly pull on the same area and can cause traction alopecia, often at the temples and sideburns.

I want to colour or perm but worry about damage. What is the gentler approach?

Colouring and perming are not off limits; what matters is how often, how far apart, and the state of your scalp. These are the principles I usually give my patients:

• One treatment at a time: in Taiwan, the labelling requirements for both hair dyes and perm products advise against doing the other treatment within a week before or after; the American Academy of Dermatology suggests perming or straightening first and waiting two weeks before colouring.
• Space out touch-ups: in dry weather you can stretch touch-ups to 8 to 10 weeks or longer, colouring only the regrowth rather than the full length each time.
• Pause if your scalp is not well: do not colour or perm when the scalp has wounds, is inflamed, flaking or freshly scratched, and do not scrub the scalp hard just before colouring.
• Keep the product off the scalp: ask your stylist to avoid the scalp as far as possible and time the product accurately, and speak up at once if it stings or burns.
• Be gentle afterwards: use conditioner after every wash, cut down on hot tools, and wear a hat in strong sun.

If you are also worried about an oily or flaky scalp after treatments and are unsure which shampoo to choose, see Do Hair Growth Shampoos Work? Ingredients, Labels and When to See a Doctor.

If you are already being treated for pattern hair loss or your hair is naturally fine, talk to your doctor about your scalp before colouring or perming. When hair is already sparse, breakage makes the visual difference more noticeable.

Can I colour or perm my hair before or after a hair transplant?

Yes, but the timing needs to fit around surgery and healing. If you colour your hair regularly, or have ever reacted to hair dye, tell the medical team at your assessment. For people with a lot of grey or white hair, the surgical team sometimes arranges colouring before surgery to make the follicles easier to see.

If you are also worried that white hair could affect a transplant, see Can You Get a Hair Transplant With White Hair? Dyeing, Harvesting, and Assessment.

After a transplant, both the recipient and donor areas need to have lost their scabs, with no weeping or obvious redness, before colouring or perming is discussed, and chemical treatments usually come later than trimming the surrounding hair with scissors. Everyone heals at a different pace; I check the wounds at follow-up before telling you when it is suitable. Please follow your surgeon’s aftercare instructions rather than copying someone else’s timeline.

If you want to know more about aftercare as a whole, see How to Care for Hair After a Hair Transplant: Washing, Sleep, Exercise & Swelling Guide.

If the thinning is confirmed as pattern hair loss, the affected area is clearly defined, the pattern is relatively stable and there is enough donor hair at the back of the head, a hair transplant can be assessed further. A transplant addresses a shortage of follicles, which is a different matter from breakage caused by chemical treatments; simple breakage is usually handled first by changing how you care for your hair.

When should you see a doctor after colouring or perming?

If any of the following apply, I would recommend seeing a doctor and having your scalp examined rather than switching to yet another hair-care product:

• Scalp redness, swelling, blisters, weeping or crusting, or swelling of the face or eyelids
• Stinging or burning of the scalp after a treatment that has not improved after a few days, or broken skin or scarring
• Losing whole hairs with the root for more than three months
• A widening parting, visible scalp at the crown, or a receding hairline or temples
• Round, patchy bald spots
• Breakage that has not improved after stopping treatments and trimming

What can you prepare before your appointment?

Take photos of the packaging or ingredient lists of the dyes and perm products you used recently, and note the treatment dates, when symptoms began, and whether in the past six months you have been ill, had surgery, given birth or started new medication. Collecting fallen hairs in a zip bag and taking a few photos of your crown and parting in the same lighting also helps.

How will the doctor assess it?

Usually the doctor takes a history, then uses a dermatoscope to check whether the shafts are broken, whether the follicles are of even thickness, and whether the scalp is inflamed. If an allergy is suspected, patch testing at a dermatology clinic may be recommended to identify ingredients to avoid in future. Once the cause is clear, the next step is to treat scalp inflammation, adjust hair care, or treat the specific type of hair loss.

A note from the doctor

In clinic I often see people who rush in, frightened, right after bleaching or perming their hair. When I look with a dermatoscope, most of their follicles are fine, and what they are losing is damaged, broken strands. In that case, giving the hair a rest and trimming off the damaged part is the first step, and the new growth is usually unaffected.

What concerns me more is a red, swollen, blistering or weeping scalp after colouring, or losing whole hairs with the root while the parting and hairline slowly change. For the first, please see a dermatologist to treat the allergy or inflammation. The second may be telogen effluvium or pattern hair loss; once the cause is clear, we can discuss treatment, or whether a transplant assessment makes sense. Every scalp is different, so an in-person assessment is still needed.

This article is general health education and does not replace an individual diagnosis.

Medical references

• Taiwan Food and Drug Administration, Ministry of Health and Welfare: Labelling requirements for hair dye labels, inserts and packaging (announcement, in Chinese)
• Taiwan Food and Drug Administration, Ministry of Health and Welfare: Labelling requirements for perm product labels, inserts and packaging (announcement, in Chinese)
• American Academy of Dermatology: How to stop damaging your hair
• American Academy of Dermatology: Coloring and perming tips for healthier-looking hair
• British Society for Cutaneous Allergy: Paraphenylenediamine (PPD) patient information
• Gavazzoni Dias MFR. Hair Cosmetics: An Overview. International Journal of Trichology (2015)
• Hwang JC, et al. Allergic contact dermatitis of the scalp: a review of an underdiagnosed entity. International Journal of Women’s Dermatology (2024)